Support for a workshop on pathogenesis by non-acute retroviruses is requested. Viruses that cause cancer, immunodeficiencies, and neuropathology will be considered. Viruses to be considered include murine leukemia viruses, avian leukosis virus, feline leukemia virus, murine mammary tumor virus, HTLV-I bovine leukemia virus, MAIDS virus, non-human lentiviruses and spumaviruses. These viruses provide important model systems for disease processes that are relevant to analogous human diseases. Please note that this is the seventh in a series of highly acclaimed workshops which began in 1986. These workshops are generally believed to contribute significantly to the dissemination and crossfertilization of ideas among the scientists in this field. Projected attendance is 120 people.